The present inventive subject matter relates to semiconductor memory devices, and more particularly, to a state based nonvolatile memory device and an error correction method thereof.
Semiconductor memory devices may be classified into volatile memory devices and nonvolatile memory devices. Volatile memory devices typically have a high read speed and a high write speed but may lose stored data when not powered. Nonvolatile memory devices maintain stored data even when not powered. Thus, the nonvolatile memory devices are often used to store data that should be preserved regardless of status of the power supply. Nonvolatile memory devices may include mask read only memory (ROM), programmable ROM (PROM), erasable programmable ROM, electrically erasable programmable ROM (EPROM) and other devices.
There is an ongoing demand for nonvolatile memory devices that can provide random access, low power consumption, high speed and high capacity. For example, current development efforts include efforts to provide nonvolatile memory devices capable of random access as an eXecute in place (XIP) memory. This may involve development of overwritable nonvolatile memory.
An overwritable nonvolatile memory may be referred to as a state-based nonvolatile memory. Unlike a flash memory device programming multi-bit data by page units, a state-based nonvolatile memory may program data of two or more bits at a time. Examples of state-based nonvolatile memory devices include ferroelectric RAM (FRAM) using ferroelectric capacitors, magnetic RAM (MRAM) using tunneling magneto-resistive (TMR) layers, phase change RAM (PRAM) using chalcogenide alloys and resistive RAM (RRAM) using a variable resistance material layer as a data storage medium.